feat(core): add google vertex ai (#12423)

Close [AI-125](https://linear.app/affine-design/issue/AI-125)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
  - Added new provider configurations `geminiVertex` and `anthropicVertex` for Google Vertex AI in backend schema, provider classes, and admin config.
  - Introduced `GeminiVertexProvider` and `AnthropicVertexProvider` classes supporting Vertex AI models with specific capabilities.
  - Expanded model options for transcription prompts with newer Gemini models.
  - Re-exported provider modules to include Vertex AI variants.

- **Improvements**
  - Extended provider architecture to support separate Vertex AI configurations and models.
  - Updated test setup to replace deprecated provider references with new Vertex variants.
  - Consolidated environment variables for server testing with a single `SERVER_CONFIG`.

- **Bug Fixes**
  - Updated mock models and import references in tests to align with new provider classes.

- **Chores**
  - Added `@ai-sdk/google-vertex` dependency for Vertex AI support.
  - Updated dependency list to include `@ai-sdk/google-vertex`.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.github/actions/server-test-env/action.yml

@@ -29,11 +29,7 @@ runs:
 
     - name: Import config
       shell: bash
+      env:
+        DEFAULT_CONFIG: '{}'
       run: |
-        printf '{"copilot":{"enabled":true,"providers.fal":{"apiKey":"%s"},"providers.gemini":{"apiKey":"%s"},"providers.openai":{"apiKey":"%s"},"providers.perplexity":{"apiKey":"%s"},"providers.anthropic":{"apiKey":"%s"},"exa":{"key":"%s"}}}' \
-        "$COPILOT_FAL_API_KEY" \
-        "$COPILOT_GOOGLE_API_KEY" \
-        "$COPILOT_OPENAI_API_KEY" \
-        "$COPILOT_PERPLEXITY_API_KEY" \
-        "$COPILOT_ANTHROPIC_API_KEY" \
-        "$COPILOT_EXA_API_KEY" > ./packages/backend/server/config.json
+        printf '%s\n' "${SERVER_CONFIG:-$DEFAULT_CONFIG}" > ./packages/backend/server/config.json